NO164251B - Separator and lubricant. - Google Patents

Abstract

A separating-and-lubricating agent in solid form for warm metal shaping, especially hot-sheet or profile rolling. The softening point of the agent is between 20 DEG and 250 DEG C., the melting point is between 30 DEG and 300 DEG C. and the shore-D-hardness at 200 DEG C. is between 20 and 80. The agent contains at least one thermoplastic polymer and/or copolymer and a lubricant for synthetic substances.

Description

The invention relates to a separating and lubricating agent in solid form for hot metal forming, especially for hot tin or profile rolling. For example, it can also be used as a mandrel lubricant in the production of fully drawn pipes.

It is known to use glass, salts and laminar lubricants on a graphite basis or aqueous emulsions with synthetic, surface-active agents as separators and lubricants in chip-free metal processing. Apart from the graphite-based laminar lubricants, all other agents are not applicable for hot tin rolling. Glass or vitreous lubricants cannot be used, as these can hardly be removed from the surface of the machined pieces. Salts as lubricants in the form of aqueous solutions lead to high corrosion of workpieces and machines. The use of lubricating and cooling fluids requires an additional device for cooling and cleaning, so that the fluid can be circulated.

To avoid these known disadvantages in the art, a solid lubricant in the form of briquettes was described in "Steel in the USSR", February 1974, pages 153 and 154, and Chemical Abstracts Vol. 81, 1974, 109708k. The solid briquette-shaped lubricant based on graphite also contains clay and surface-active additives and is pressed by a device against the work rolls in a rolling mill for steel, whereby a thin film of lubricant is applied to the work rolls. However, there are still disadvantages to this lubricant, as stated by Meleshko, Tubol'tsev and Adamskii in "Steel in the USSR", October 1979,

pages 515-519. According to page 516, left column, it was impossible to achieve a finely distributed, uniform lubricant film over the entire width and circumference of the roller when pressing the lubricant briquettes onto the rollers. This led to non-uniform surface loading of the rolls and sheet metal and to destabilization of the rolling process.

It was a task for the invention to propose an in and for

solid lubricant which softens or melts at elevated temperatures, which does not have the aforementioned disadvantages and which also

apart from hot plate and profile rolling can also be used for other purposes, such as lubrication of mandrels or mandrel bars when producing fully drawn pipes, for example by continuous or Pilger methods.

According to the invention, this is achieved by means of a separating

and lubricant according to claim 1.

The separating and lubricating agent according to the invention contains a thermoplastic polymer and/or copolymer bg a release agent for plastics.

Depending on the requirements for release agents and lubricants, it can

further additives are also used. Such additives can be a solid lubricant, a wetting agent, an adhesive, a surface-modifying agent, fibers and/or clay.

Appropriately contains separators and! the lubricant two thermoplastic polymers and/or copolymers.

y

As thermoplastic polymers and/or copolymers, polyolefins, vinyl resins, acrylic and methacrylic resins, polyesters, polyamides, thermoplastic polyurethanes, polyoxymethylene, polyoxyethylene, polyoxypropylene, polycarbonates, polyetherimides, polyphenylene oxides or sulphides, thermoplastic cellulose derivatives or hydrocarbon resins can be used in quantities from 1 to 70% by weight.

If according to an appropriate embodiment

if two thermoplastic polymers and/or copolymers are used, the polymer may have the same molecular structure per se, but have different chain lengths. Examples of this are polyethylenes, coumarone-inden resins, hydrocarbon resins.

Other suitable mixtures of two different polymers and/or copolymers are, for example, polyethylene with polyisobutylene and polymethylmethacrylate with polymethacrylate. These polymers are inherently incompatible. A mixture of polymers or copolymers has proven to be particularly advantageous, which, as they are mutually compatible, can be introduced step by step, for example polystyrene with 2,6-dimethyl-1,4-phenylene oxide.

According to the invention, the separating and lubricating agent contains a release agent. This is chosen from among fatty acids and soaps.

The addition of an adhesive to the polymers or copolymers should improve adhesion to the metal rafts and lower the softening temperature of the mixture: As a rule, rosin derivatives, terpene resins or hydrocarbon resins, coumarone-inden resins and the plasticizers that are used

in

usually used in connection with thermoplastics, such as those listed in "Modem Plastic Encyclopedia (1983)".

The separating and lubricating agent according to the invention also contains a solid lubricant, namely of graphite. The effect of this is known in and of itself.

A wetting agent can be added to disperse the solid lubricant in the release agent and lubricant and increase adhesion to the metal. The wetting agent causes a softening of the surface of the metal ["Rehbinder-Effekt", P.A: Rehbinder, E.D. Scukin, Les Phenoménes de surface dans la déformation et la fracture des solides - Seminaire de Mecanigue des Surfaces ISMCM - CNRS

(1971)], which in the case of friction leads to low coefficients of friction and in the smoothing of the surface to low, uniform wear of the friction partner. For the same reason, a surface modifying agent can be used. A titanate, preferably isopropyltriisostearyl titanate, is used as this agent. In order to be able to produce a mold of the separating and lubricating agent with increased mechanical strength, it can be advantageous to mix fibers from the range of polyethylenes, polypropylenes, polyamides, polyacrylonitriles, polyesters, carbon or glass. With the possible addition of plastic inorganic raw materials from the range of clay minerals, such as kaolins, clays, bentonites, talc or vermiculite, it is achieved that the softness and friction coefficient of the separating and lubricating agent can be affected. A separating and lubricating agent, for example for hot plate and profile rolling, can have the following proportions of the individual components: 1 to 70% by weight polymer and/or copolymer and 1 to 50% by weight release agent, 1 to 90% by weight solid lubricant, up to 10 wt% wetting agent, 1 to 70 wt% adhesive, 1 to 30 wt% plasticizer, up to 2 wt% surface modifier, up to 20 wt% clay and up to 5 wt% fibers. For use as a mandrel lubricant, the composition of the release agent and lubricant can conveniently be present in the following proportions: 30 to 70% by weight polymer and/or copolymer, 1 to 50% by weight release agent, 20 to 50% by weight adhesive, 10 to 90% by weight solid lubricant, up to 7% by weight of wetting agent, up to 2% by weight of surface modifier and up to 5% by weight of fibres. The mixture of the components according to the invention must give a separating and lubricating agent which has a solid form at normal temperature. When, for example, the separating agent and lubricant is used in hot tin rolling and comes into contact with a hot roller, or when producing fully drawn tubes on a hot mandrel is heated and thereby softened, it can form a film that is homogeneous in composition and thickness by friction and/or melting on the roll or on the mandrel. This film is, on the one hand, waterproof, so that the large amounts of cooling water that flow over the rollers or the mandrel do not affect the film.

On the other hand, the film is easily transferred from one

waltz to another. Thus, for example, it is possible with hot plate or profile rolling to apply the separating agent and lubricant to the pressure rollers, which in turn transfer the separating agent and lubricant to the working rollers, whereby a film is always obtained that is homogeneous in composition and thickness.

When using the separating and lubricating agent, especially as a mandrel lubricant, the solid lubricant ensures that even under certain difficult conditions, such as high pressure, high temperatures and friction between tool and workpiece, it does not experience excessive loads and stresses.

The separating and lubricating agent is produced by mixing the components in heat, for example with a kneader and pressing the individual components into the desired shape. The processing can also be carried out in an extruder or with spraying technique.

The finished elements are solid at normal temperature and have a softening point from 20 to 250°C.

The Shore-D hardness is 20 to 50 for elements with a low softening point and 50 to 80 for elements with a high softening point.

The melting point is at 30 to 300°C. The cold compressive strength must be 5 to 500 kg/cm<2>.

With the separating and lubricating agent according to the invention, it is achieved that the energy that must be used, for example to roll sheet metal and profiles, is significantly reduced due to the good separating and lubricating effect. The quality of the surface of the processed workpiece is also improved and exhibits, for example, little roughness. The separating and lubricating agent also leads to greater operational reliability, as the lubrication effect can be controlled by choosing the additives, and a too good lubrication effect can thereby be avoided, which leads to a transparent look.

The film thickness can also be well regulated, and films with a thickness of 50 to 200 pm can be applied. As the agent exhibits high lubrication performance, a film thickness of an average of 1 to 2 pm is sufficient in many cases. Compared to known oil-based lubricants, steam and smoke formation and pollution of the surroundings are eliminated.

This mixture produces a transfer film, which lubricates at a temperature of 80 to 90 "C.

EXAMPLE 2

This mixture gives a transfer film, which lubricates between 50 and 100°C.

EXAMPLE 3

This mixture produces a transfer film, which lubricates at a temperature of 100 to 150°C.

EXAMPLE 4

This mixture produces a transfer film at a temperature of 50 to 10'C.

The reference figures indicate the effect of the components as:

(1) thermoplastic polymer and/or copolymer

(3) adhesive

(4) lubricant for synthetic substances (release agent)

(5) fatty acid based moisturizer

(6) surface modifier

(7) solid lubricant

(9) clay.

Claims (2)

1. Separating agent and lubricant in solid form for hot metal forming, especially for hot sheet or profile rolling, characterized by the softening point being 20-250°C, the melting point 30-300°C and the Shore-D hardness at 20°C is 20-80, whereby the agent contains 1-90% by weight of a solid lubricant of graphite, 1-70% by weight of at least one thermoplastic polymer and/or copolymer, and 1-50% by weight of a release agent from the range of fatty acids or soaps, 1 -10% by weight wetting agent, 1-10% by weight adhesive, as well as up to 2% by weight of a titanate surface modifier. in 2. Means as stated in claim 1, characterized in that it contains clay.